Patent GB-1378602-A (GB)
Title: Needle assemblies for use with apparatus for collecting samples of blood
IPC: A61B5/15
Filed: 1973-05-02
Abstract: 1378602 Blood sampling device BECTON DICKINSON & CO 2 May 1973 [28 June 1972] 20920/73 Heading A5R [Also in Division F2] Blood sampling apparatus: A blood sampling apparatus comprises a needle assembly having means for indicating when a renapuncture is accomplished and then transferring blood froma patient into an evacuated container (39), Fig. 2, (not shown) whilst preventing backflow into the patient, and means for automatically blocking the blood flow while changing one container for a successive container, the indicating and backflow preventing means consisting of a transparent housing 21, Fig. 10, defining a chamber 26, Fig. 3, a forward end 22 including a cannula 24 extending from the housing 21, a rear end 23 adapted to be coupled to the container (39), a passageway for directing blood from the blood vessel through the housing 21 to the container (39), a valve assembly in the chamber 26 and movable from an unarmed position in which passages 54 allow the flow of blood to the chamber 26, to an unarmed position in which a resilient elastomeric valve member 27 stops the flow of blood to the chamber 26, the valve member 27 being responsive to reduced pressure when the rear end 23 is coupled with the evacuated container (39) to deform the valve member 27 and automatically open a passage 55 to the container (39), and automatically close the passage 55 when the pressure in the rear end 23 increases, to prevent backflow of blood to the patient. Needle Assembly: The cannula 24 is adhesively secured to the front end 22 which is frusto-conical and engages the cylindrical rear end 23 to form the chamber 26. The rear end 23 has a cannula 25 secured thereto and a screw thread 37 for engaging a holder (38) for the container (39) which has a self sealing stopper (41) pierceable by the cannula 25. The housing 26 accommodates a rigid cage 28 adhesively secured to the cannula 25, and the valve member 27 which is a sleeve in which the passages 54 and a slit defining the passage 55 are formed. The walls of the valve member 27 and the cage 28 define a space therebetween. The cage 28 has apertures 48 in its side and the cannula 25 has an aperture 45 in its side near the cage 28. An elastomeric disc 30 forms a seal with an annular bead 46 on the rear end 23 and is held there by a retaining disc 29 which fits tightly in a reduced bore 56 of the end 23. The cannula 25 slides in the rear end 23 while maintaining a seal withthe disc 30. The housing 21 and the cage 28 are formed of a transparent plastics material and the sleeve 27 may be formed of a transparent elastomeric material. Operation: Initially, the needle assembly is in the unarmed position shown in Fig. 3 and the cannula 24 inserted in a vein. Blood flows through the passages 54 and 48 into the transparent housing 21 to indicate a successful renapuncture. The container (39) is pushed against the cannula 25, which moves the cage 28 with it to engage a flange 50 on the sleeve 27 and move it so that the cannula 24 enters the sleeve 27 and occludes the passages 54 and the sleeve 27 finally abuts the end 22. The cannula 25 then pierces the stopper (41). The pressure differential across the slit 55 opens it so that blood flows through it and through the apertures 48, 45 and into the container (39) as shown in Fig. 7, (not shown). When the pressure in the container (39) rises the slit 55 closes and prevents back flow. An additional container may be filled by withdrawing the container (39), which retracts the cannula 25 and the cage 28 so that itabuts the end 23 and the aperture 45 no longer communicates with the chamber 26 so that further flow of blood is stopped. The procedure is repeated with the other containers but from the same renapuncture.